Research On Energy Storage Scheme Of Interconnected Power Supply System Of Electrified Railway

The railway construction in our country is in full swing,but in the western region with complex terrain,the power system is relatively weak,and it also undertakes the power supply of traction load and other loads,which requires high reliability and adaptability of traction power supply system and power system.Moreover,phase splits are widely used in electrified railways to change the phase sequence of power supply,although they greatly improve the three-phase voltage imbalance caused by single-phase traction load,a series of problems such as train traction loss and locomotive passing split phase follow.In addition,with the running speed and traction power increased of the train,the regenerative braking energy has not been effectively recovered.In order to improve the situation above and respond to "double carbon" plan,the main research contents of this paper are as follows:The energy storage scheme(ESS)of Interconnected Power Supply System of Traction Substation Group is proposed by the comparison of the through power supply system and the analysis of the traction transformers,then the location of the energy storage device and the division of the traction substation group are analyzed,and two energy storage schemes,the centralized energy storage scheme and the distributed energy storage scheme,are designed and compared,and four working conditions of the energy scheme are divided and determined.A super-capacitor energy storage scheme(SCESS)and a hybrid energy storage scheme(HESS)are proposed,the topology,circuit model and parameters of the two schemes are designed respectively,and a hierarchical control strategy based on upper energy management layer and lower circuit control layer is built.For the energy management strategy,a dynamic predictive charge-discharge threshold determination method based on fuzzy control technology is proposed in the SCESS,which can recover 100% of the regenerative braking energy(RBE)within the allowable range of the state of charge(SOC),reduce the load fluctuation,and make the three-phase voltage imbalance meet the national standard;In the HESS,energy management is divided into two parts: The external part also determines the adaptive reference charge-discharge power based on SOC,internally,based on the energy and power characteristics of the super-capacitor and the battery,a time constant correction method is proposed to allocate power reasonably so that the sum of the power of the super-capacitor and the battery approaches the reference power.In the lower-layer control,transient current control technology is adopted by the AC-DC converter,and power control is applied in the DC-DC converter of energy storage device.Finally,the one-day traction load data of three traction substations of the same line are used in program to verify the energy management strategies of the two schemes respectively;The Interconnected Power Supply System model with energy storage device is built in Simulink,and the typical working conditions are selected for simulation verification.The results show that both two energy storage schemes can realize the recovery of regenerative energy immediately and effectively,cut the peak and fill the valley of the traction load,make the three-phase voltage imbalance degree meet the standard,which have great economic benefits.